I am trying to create a document that will receive multiple URLs over the time of Googhe Sheet files, where I want to use IMPORTRANGE to extract the same range everytime. I want it to work without having to modify anything, except adding the URL in a list each time I need it to. The problem is that the data I want to import from those URLs are multirow ranges. And I cant figure out a way to import everything in one formula, or by expending my formula on all the cells of a column.
For example:
I have those two source Google Sheet files :
Source A:
Source B:
In my main file, I want to have an URL sheet, and a result sheet like below. In the future, if I have a new source file, I want to only have to add its URL to the URL list:
URL list: 
Result: 
My best shot at this problem for the moment is the following formula:
={IMPORTRANGE('URL List'!A2; "A2:B4"); IMPORTRANGE('URL List'!A3; "A2:B4")}I have the result I was looking for, but if I have to add a new URL, I have to modify my formula. And I didn't find a way to update the literal array when the URL list is modified.
Also, if I tried to simply use =IMPORTRANGE('URL List'!A2; "A2:B4") on my first cell and expand it on all the cells below in the result sheet, I have the error #REF!, saying that the result didn't expand to not delete the data in the following cells.